A method using a chemically amplified resist is known as a method to form a resist pattern on a semiconductor wafer, a glass substrate for a liquid crystal display, or the like. When such a resist is subjected to exposure (pattern exposure) using a pattern mask, performed by means of an exposure apparatus, an acid is generated in exposed portions of the resist, and the acid diffuses upon heating of the resist, whereby the resist becomes, for example, alkali-soluble. Therefore, a pattern is formed by supplying a developer to the resist film.
As circuits are becoming increasingly finer, a high resolution is required even for a fine pattern in a resist pattern forming process. Extreme ultraviolet (EUV) exposure is known as a method that meets the requirement. EUV exposure, however, has the following problem: To increase the light intensity of an exposure light source necessitates a significant scale-up of the apparatus and thus entails a considerably increased cost. This makes an appreciable increase in the light intensity quite difficult, posing the problem of low throughput (number of substrates processed per unit time).
Patent document 1 discloses a method which involves performing a first pattern forming step by exposure of a wafer to light, using a chemically amplified resist, and then performing a second pattern exposure step by exposure of the wafer to an electron beam. However, the method disclosed in the patent document necessitates the two steps of pattern exposure and, in addition, requires heating of the wafer after each exposure step. This method thus needs improvement from the viewpoint of throughput. Patent document 2 discloses a resist composition for forming a resist pattern by EUV exposure and a method for forming a resist pattern. This document, however, addresses the resist composition itself, and is directed to a technical problem significantly different from that of the present invention.